1. Field of the Invention
The present invention relates to an image forming apparatus capable of conveying sheets with images formed thereon at one side thereof so as to again form images thereon at the other side thereof while reversing them.
2. Description of the Related Art
With regard to image forming apparatuses such as copying machines, printers or the like, there is a demand for increasing the number of sheet cassettes and/or sheet capacity of the sheet cassettes without changing or increasing the size or installation space of an apparatus main body. Cassettes having a width equal to that of the apparatus main body can flexibly accommodate varying sizes such as from a smaller size of A4 to a larger size of A3 or the like, but when the cassettes contain A4 size sheets, waste spaces being not actually used will be created.
In view of such a situation, consideration is given to the arrangements of cassettes and/or sheet decks so as to make effective use of the space inside the apparatus main body. For instance, special sheet cassettes dedicated to smaller sizes up to A4 are arranged in an empty space inside the apparatus main body, or two small cassettes or sheet decks less in width than the apparatus main body are arranged side by side in the right and left (i.e., widthwise or transverse) direction with a large cassette capable of accommodating a larger size being disposed thereunder, so as to meet the users' demand of increasing sheet capacity of the cassettes or sheet decks.
In copying machines and printers, the volume occupied by image forming units is increasing in order to achieve coloring in recent years, but in this case, it becomes difficult to keep both the size of the apparatus main body and the sheet capacity at levels equal to those in the conventional ones. Also, in monochrome machines, the demand for further increasing sheet capacity is increasing.
Thus, in order to meet the demand of increasing the sheet capacity while keeping the size of the apparatus main body equal to that of the conventional one, it is necessary to reduce the space occupied by those component parts or devices which are associated with the conveyance of the sheets.
Moreover, in conventional image forming apparatuses in which sheet cassettes or sheet decks are vertically arranged one over another, paper jams caused in a sheet reversing path 101, as shown in FIG. 9, have been cleared or remedied by opening a side door of an apparatus main body. FIG. 9 is a cross sectional view of such a conventional image forming apparatus.
Therefore, in cases where sheet finishing applications such as a sorter, a finisher, etc., are arranged at a side of the apparatus main body at which the side door is disposed, it is necessary to separate these sheet finishing applications from the apparatus main body for handling or clearing paper jams, thus resulting in poor usability as well as requiring an ample space for the separation of the sheet finishing applications.